Deploy all tagged commits to PyPI, even if not on master

Depending on the order commits are tagged vs. merged into master, a tag
may never be deployed under the old conditions.

Safer to deploy all tags, whether they are merged yet or not. Up to tagger
to ensure they are merged as appropriate.

.travis.yml

@@ -13,7 +13,7 @@ script:
 jobs:
   include:
     - stage: deploy
-      if: branch = master AND tag IS present
+      if: tag IS present
       python: 3.8
       script: skip
       deploy:
@@ -24,4 +24,3 @@ jobs:
         distributions: "sdist bdist_wheel"
         on:
           tags: true
-          branch: master